High-efficiency neutral-point-clamped transformerless MOSFET inverter for photovoltaic applications

Here, a highly efficient MOSFET neutral-point-clamped (M-NPC) transformerless inverter is proposed for photovoltaic (PV) applications. By employing super-junction metal-oxide-semiconductor field-effect transistor (SJ-MOSFET) as well as silicon carbide (SiC) diodes, high efficiency is achieved. Furthermore, the common-mode voltage (CMV) is completely clamped at half of the input voltage with clamping branch. Therefore, leakage current is eliminated. The performances of different topologies, in terms of CMV, leakage current, total harmonic distortion (THD), losses, and efficiency, are compared with the proposed M-NPC topology. The analyses are carried out theoretically via MATLAB/Simulink, and further validated with experimental tests. The experimental results show maximum efficiency of 98.5% and European efficiency of 97.65%.